U.S. patent application number 11/747444 was filed with the patent office on 2008-04-03 for method for fabricating semiconductor device.
This patent application is currently assigned to HYNIX SEMICONDUCTOR INC.. Invention is credited to Whee-Won Cho, Cheol-Mo Jeong, Jung Geun Kim, Seong-Hwan Myung.
Application Number | 20080081465 11/747444 |
Document ID | / |
Family ID | 39261630 |
Filed Date | 2008-04-03 |
United States Patent
Application |
20080081465 |
Kind Code |
A1 |
Kim; Jung Geun ; et
al. |
April 3, 2008 |
Method for Fabricating Semiconductor Device
Abstract
A method for fabricating a semiconductor device, in which a
lifting phenomenon can be prevented from occurring in forming an
amorphous carbon film on an etched layer having tensile stress.
According to the invention, since a compression stress on the
etched layer or the amorphous carbon film can be reduced or a
compression stress film is formed between the etched layer or the
amorphous carbon film to prevent a lifting phenomenon from
occurring and thus another pattern can be formed to fabricate a
highly integrated semiconductor device.
Inventors: |
Kim; Jung Geun; (Seoul,
KR) ; Jeong; Cheol-Mo; (Icheon-si, KR) ; Cho;
Whee-Won; (Chungcheongbuk-do, KR) ; Myung;
Seong-Hwan; (Kyeongki-Do, KR) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
233 S. WACKER DRIVE, SUITE 6300, SEARS TOWER
CHICAGO
IL
60606
US
|
Assignee: |
HYNIX SEMICONDUCTOR INC.
Kyoungki-do
KR
|
Family ID: |
39261630 |
Appl. No.: |
11/747444 |
Filed: |
May 11, 2007 |
Current U.S.
Class: |
438/660 ;
257/E21.029; 257/E21.209; 257/E21.314; 257/E21.477 |
Current CPC
Class: |
H01L 21/0276 20130101;
H01L 21/32139 20130101; H01L 29/40114 20190801 |
Class at
Publication: |
438/660 ;
257/E21.477 |
International
Class: |
H01L 21/44 20060101
H01L021/44 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2006 |
KR |
2006-96199 |
Claims
1. A method of fabricating a semiconductor device comprising the
steps of: forming an etched film on a semiconductor substrate; and
forming an amorphous carbon film on the etched film, wherein when
the etched film has a tensile stress, the amorphous carbon film has
a compression stress.
2. A method of fabricating a semiconductor device according to
claim 1, comprising forming the amorphous carbon film at
100.degree. C. to 400.degree. C.
3. A method of fabricating a semiconductor device according to
claim 1, wherein the etched film is a conductive layer.
4. A method of fabricating a semiconductor device comprising the
steps of: forming an etched layer having a tensile stress on a
semiconductor substrate; depositing an amorphous carbon film on the
etched layer; and performing a heat treatment to eliminate the
tensile stress on the etched layer.
5. A method of fabricating a semiconductor device according to
claim 4, comprising performing the heat treatment under an argon
atmosphere at 300.degree. C. to 500.degree. C. for 0.5 hours to two
hours.
6. A method of fabricating a semiconductor device according to
claim 4, comprising performing the heat treatment under an argon
atmosphere at 300.degree. C. to 500.degree. C. for one minute to 20
minutes through a Rapid Thermal Annealing process.
7. A method of fabricating a semiconductor device according to
claim 4, wherein the etched layer is a conductive layer.
8. A method of fabricating a semiconductor device comprising the
steps of: forming an etched layer on a semiconductor substrate;
forming a compression stress film having a predetermined
compression stress on the etched layer; and depositing an amorphous
carbon film on the compression stress film, wherein the tensile
stress on the amorphous carbon film can be reduced due to the
compression stress on the compression film.
9. A method of fabricating a semiconductor device according to
claim 8, wherein the compression stress film comprises at least one
of a PE nitride film, an oxide film, an SiON film, and a strontium
oxide film (SrOx).
10. A method of fabricating a semiconductor device according to
claim 8, wherein the etched layer is a conductive layer.
11. A method of fabricating a semiconductor device according to
claim 10, comprising forming the conductive layer of one of
Chemical Vapor Deposition (CVD) tungsten, aluminum, TiCl4-TiN, and
polysilicon.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The priority of Korean patent application number
10-2006-96199, filed on Sep. 29, 2006, the disclosure of which is
incorporated by reference in its entirety, is claimed.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a method for fabricating a
semiconductor device and, more particularly, to a method for
fabricating a semiconductor device in which a lifting phenomenon
can be prevented from occurring in forming an amorphous carbon film
on an etched layer having tensile stress.
[0003] As semiconductor devices have become more highly integrated,
the devices have to be formed in a high density on a predetermined
cell area and therefore unit devices such as a transistors and
capacitors, etc. decrease in size. In particular, as a design rule
decreases in a memory device such as a flash memory, semiconductor
devices that are formed inside cells decrease generally in size.
Recently, a minimum line width of a flash memory device is formed
equal to or less than 0.1 .mu.m, and further as required to be
equal to or less than 60 nm. Therefore, several problems arise in
fabricating semiconductor devices forming a cell and various
solutions has been tried to solve the aforementioned problems.
[0004] In particular, as to a step of forming a pattern of metal
wire, etc., in the prior art, a reflection preventing film was
formed of SiON, etc., and a hard mask was formed of a nitride film
such as SiN, etc., and then a photolithography process was
performed using such resulting films. However, there is a
limitation to the step of fabricating a semiconductor device having
a minute line width equal to or less than 60 nm. As a result, a
solution has been proposed, in which a reflection preventing film
and a hard mask are formed at the same time using a amorphous
carbon film and photolithography is performed in order to form a
minute pattern in fabricating a semiconductor device having a line
width equal to or less than 60 nm.
[0005] However, when the reflection preventing film and the hard
mask are formed using a amorphous carbon film, a problem arises in
that a lifting phenomenon occurs, which does not occur in forming
the reflection preventing film and the hard mask using SiON and
SiN.
[0006] Here, this lifting phenomenon relates to a stress
concentration factor Kc on a stacked layer. Typically, when the
stress concentration factor on a stacked layer is large, the
lifting phenomenon may occur due to a low interfacial bonding
force. However, when the stress concentration factor is small on
the stacked layer, the lifting phenomenon may not occur due to a
high interfacial bonding force. In addition, the stress
concentration factor is proportional to a square root of the stress
applied to a film multiplied by a thickness thereof and the total
stress concentration factor of a stacked layer is a sum of the
respective stress concentration factors on each layer. The stress
concentration factor is represented by a formula as follows.
Kc=.OMEGA..times.stress.times.thickness 2 (.OMEGA.=1.46) [Formula
1]
[0007] The following Table 1 shows stresses and stress
concentration factors on an amorphous carbon film and a tungsten
layer formed by a Chemical Vapor Deposition (hereinafter referred
to as "CVD"), respectively, and a stress concentration factor on
stacked layers formed by stacking them, according to the prior art.
In addition, FIG. 1 is a sectional view showing the
aforementioned-stacked layer.
TABLE-US-00001 TABLE 1 Film Thickness (.ANG.) Stress (dyn/cm.sup.2)
K.sub.c (MPa/m.sup.0.5) Amorphous carbon 1500 9.00e8 0.051 film CVD
tungsten film 800 1.5e10 0.619 Total K.sub.c on the Stacked layer
0.67
[0008] Generally, the CVD tungsten film that is used as a metal
wire of a flash memory has a large tensile stress of 2000 MPa (2e10
dyn/cm2) and the amorphous carbon film has a large tensile stress
of 90 MPa (0.9e9 dyn/cm.sup.2) at a forming temperature of
550.degree. C. Therefore, when an amorphous carbon film is formed
over a CVD tungsten film to form a metal wire of a flash memory,
two layers having large tensile stresses, respectively, are
stacked. As a result, as shown in Table 1, the stress concentration
factor becomes relatively large and thus a lifting phenomenon
occurs on an interface, as shown at portion A of FIG. 1.
[0009] To solve the problem of a lifting phenomenon occurring on an
interface, a tungsten film formed by Physical Vapor Deposition
(hereinafter referred to as "PVD"), rather than CVD tungsten film
having a large tensile stress, has been used.
[0010] The following Table 2 shows stresses and stress
concentration factors on an amorphous carbon film, a PVD tungsten
layer, and PE nitride film (Plasma Enhanced nitride), respectively,
and a stress concentration factor on stacked layers formed by
stacking them. In addition, FIG. 2 is a sectional view showing the
aforementioned-stacked layer.
TABLE-US-00002 TABLE 2 Film Thickness (.ANG.) Stress (dyn/cm.sup.2)
K.sub.c (MPa/m.sup.0.5) Amorphous carbon 2000 9.00e8 0.059 film PE
nitride film 300 -2.60e9 -0.066 PVD tungsten film 5.00e9 0.206
Total K.sub.c on the Stacked layer 0.199
[0011] Referring to Table 2, since the value of a stress
concentration factor on the stacked layer formed, as the
aforementioned way is relatively small, a lifting phenomenon does
not occur, as shown in FIG. 2. However, since a burial step of a
metal contact is difficult when a PVD tungsten film is used, in
order to perform a step of using a PVD tungsten film, a prior CVD
tungsten film is buried to form a metal contact and then a metal
wire is formed using PVD tungsten. Accordingly, the numbers of
steps increase to become complicate in using PVD tungsten.
SUMMARY OF THE INVENTION
[0012] To solve the problem, the invention provides a method of
fabricating a semiconductor device in which a tensile stress on an
etched layer or an amorphous carbon film can be reduced in forming
an amorphous carbon film, or a compression stress film is formed
between the etched layer and the amorphous carbon film and thus a
lifting phenomenon can be prevented from occurring.
[0013] A method of fabricating a semiconductor device according to
one embodiment of the invention includes the steps of forming an
etched film on a semiconductor substrate, and forming an amorphous
carbon film on the etched film, wherein when the etched film has a
tensile stress, the amorphous carbon film has a compression
stress.
[0014] The amorphous carbon film is preferably formed at
100.degree. C. to 400.degree. C.
[0015] A method of forming a semiconductor device according to
another embodiment of the present invention may comprise the steps
of forming an etched layer having a tensile stress on a
semiconductor substrate, depositing an amorphous carbon film on the
etched layer, and performing a heat treatment to eliminate the
tensile stress on the etched layer.
[0016] The heat treatment is preferably performed under an argon
atmosphere at 300.degree. C. to 500.degree. C. for 0.5-2 hours.
[0017] The heat treatment is preferably performed under an argon
atmosphere at 300.degree. C. to 500.degree. C. for one minute to 20
minutes through a Rapid Thermal Annealing process.
[0018] A method of forming a semiconductor device according to
another embodiment of the invention may include the steps of
forming an etched layer on a semiconductor substrate, forming a
compression stress film having a predetermined compression stress
on the etched layer, and depositing an amorphous carbon film on the
compression stress film, wherein the tensile stress on the
amorphous carbon film can be reduced due to the compression stress
on the compression film.
[0019] The compression stress film preferably forms at least one of
a PE nitride film, oxide, SiON, and strontium oxide film
(SROx).
[0020] The etch layer is preferably a conductive layer.
[0021] The conductive layer is preferably formed of one of CVD
tungsten, aluminum, TiCl4-TiN, and polysilicon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of the disclosure, illustrate embodiments of the
invention and together with the description serve to explain the
principles of the invention. In the drawings:
[0023] FIG. 1 is a sectional view showing an amorphous carbon film
and a CVD tungsten film formed according to the prior art.
[0024] FIG. 2 is a sectional view showing a PVD tungsten film, a PE
nitride film and an amorphous carbon film formed according to the
prior art.
[0025] FIG. 3 is a sectional view showing a semiconductor device
including a stacked layer of a HDP oxidation film, a CVD tungsten
film and Ti--TiN film.
DESCRIPTION OF SPECIFIC EMBODIMENTS
[0026] Reference will now be made in detail to the preferred
embodiments of the invention, examples of which are illustrated in
the accompanying drawings.
[0027] In the following, an embodiment of the invention will be
described.
[0028] In a typical NAND flash memory process, a gate electrode is
formed of a tungsten silicide (WSi), etc. and a nitride film and an
interlayer insulation film are formed thereover and a stacked layer
of a metal wire/a barrier metal layer and then a hard mask film is
formed of a nitride film and an oxidation film, etc. At this time,
when a PE-TEOS film is formed of the inter layer insulation film
and a stacked layer of CVD tungsten film/Ti--TiN film is formed of
the stacked layer, a lifting phenomenon occurs on the CVD tungsten
film and the CVD tungsten film due to a tensile stress of the CVD
tungsten film. Here, a stress concentration factor of the entire
structure thereof is 0.67 MPa/m0.5.
[0029] Meanwhile, when the inter layer insulation film is formed of
a HDP (High Density Plasma) oxidation film and a stacked layer of
CVD tungsten film/Ti--TiN film is formed of the stacked layer, as
shown in FIG. 3, a lifting phenomenon does not occur on the CVD
tungsten film and the Ti--TiN film. At this time, a stress
concentration factor of the entire structure thereof is 0.49
MPa/m0.5. Here, it is taught that when the stress concentration
factor is large, the lifting phenomenon may occur, and that when
the stress concentration factor is equal to or less than 0.49
MPa/m0.5, the lifting phenomenon does not occur on the CVD tungsten
film.
[0030] Accordingly, when a stacked layer is formed by stacking
films having tensile stress and further the tensile stress are
reduced for the stress concentration factor of the stacked layer to
be equal to or less than 0.49 MPa/m0.5, the lifting phenomenon is
prevented from occurring. For this purpose, when an amorphous
carbon film is stacked over an etched layer having a tensile
stress, as a hard mask and a reflection preventing film, the
tensile stress of the amorphous carbon film and the etched layer is
to reduce, or a compression stress film having a compression stress
is formed between the stacked layers and thus the lifting
phenomenon can be prevented. Here, the etched layer is formed as a
conductive layer; preferably, it may be one of CVD tungsten,
aluminum, TiCl4-TiN and polysilicon.
[0031] Details of this embodiment will be as follows.
Embodiment 1
[0032] An amorphous carbon film having a compression stress is
formed. Typically, the amorphous carbon film has a tensile stress
of about 90 MPa at a forming temperature of 550.degree. C. Here,
when the amorphous carbon film is formed at below this temperature,
preferably, 100.degree. C.-400.degree. C., the amorphous carbon
film has a compression stress. For example, the amorphous carbon
film is formed at 300.degree. C., it has a tensile stress of about
330 MPa.
[0033] Accordingly, when an amorphous carbon film is formed over
the etched layer, the amorphous carbon film is formed at a range of
100.degree. C. to 400.degree. C. and thus a lifting phenomenon on a
stacked layer can be prevented. The following Table 3 shows
stresses and stress concentration factors on a CVD tungsten film
and an amorphous carbon film formed at 300.degree. C.,
respectively, and a stress concentration factor on stacked layers
formed by stacking them.
TABLE-US-00003 TABLE 3 Film Thickness (.ANG.) Stress (dyn/cm.sup.2)
K.sub.c (MPa/m.sup.0.5) Amorphous carbon 2000 -3.30e+09 -0.215 film
CVD tungsten film 800 1.50e+10 0.619 Total K.sub.c on the Stacked
layer 0.404
[0034] Referring to Table 3, the stress concentration factor on the
stacked layer is 0.404 MPa/m0.5, and thus a lifting phenomenon does
not occur.
Embodiment 2
[0035] To reduce a tensile stress on an etched layer, a heat
treatment process against the etched layer is performed. The heat
treatment process for reducing a tensile stress on the etched layer
is performed under an argon atmosphere at 300.degree. C. to
500.degree. C. for 0.5 hours to two hours, or under argon
atmosphere at 300.degree. C.-500.degree. C. for one minute to 20
minutes through a Rapid Thermal Annealing process.
Embodiment 3
[0036] A film having a compression stress is formed between a
stacked layer of an etched layer and an amorphous carbon film. The
film having a compression stress includes a Plasma Enhanced nitride
film, an oxide film, SiON film and a strontium oxide film (SrOx),
etc. The following Table 4 shows stresses and stress concentration
factors on a CVD tungsten film, an amorphous carbon film, and a PE
nitride film respectively, and a stress concentration factor on
stacked layers formed by stacking the PE nitride film between the
CVD tungsten film and the amorphous carbon film.
TABLE-US-00004 TABLE 4 Film Thickness (.ANG.) Stress (dyn/cm.sup.2)
K.sub.c (MPa/m.sup.0.5) Amorphous carbon 2000 9.00e+08 0.059 film
PE nitride film 300 -2.60+09 -0.066 CVD tungsten film 800 1.5e+10
0.619 Total K.sub.c on the Stacked layer 0.338
[0037] Referring to Table 4, the stress concentration factor on the
stacked layer is 0.038 MPa/m0.5, and thus a lifting phenomenon does
not occur.
[0038] According to the method for fabricating a semiconductor
device of the invention, when an amorphous carbon film is stacked
as a hard mask and a reflection preventing film on a etched layer
having a tensile stress, a lifting phenomenon does not occur and
thus minute pattern can be formed. Accordingly, highly integrated
and minute semiconductor can be fabricated.
* * * * *